QMagnetometer doesn't seem to work on iOS

import QtQuick 2.9
import QtQuick.Window 2.2
import QtSensors 5.0

Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World") 
    Magnetometer {
        id: mag
        active: true
    }    
    Text {
        anchors.fill: parent
        text: {
            if (!mag.reading) return "WAIT";
            return "M:\n" + mag.reading.x + "\n" +
                            mag.reading.y + "\n" +
                            mag.reading.z;
        }
    }
}